Description:Body thin and cylindrical, with up to 126 segments.Prostomium is conical, small, without eyes. First segment without chaetae, with two reddish eyes dorsally.Thorax with 10 chaetigers. First 4 segments with long, winged capillary chaetae only, segment 5 and following segments with hooks only; thoracichooks with three rows of small teeth over the large terminal tooth, hooded.Abdominal segments are longer than thoracic, but become shorter towards the posterior end. Abdominal noto- and neuropodia with tori, which bear hooks. Abdominalhooks are much shorter than the thoracichooks. Abdominaltori are set on the posterior 1/3 of the segment; thoracicparapodia in the middle of the segment (M. fragilis-detail).Genital hooks and gills absent.Pygidium with 1 ventral anal cirrus .

Size:Up to 50-60 mm for more than 100 segments.

Colour:Colourless.

Habitat: Lives in vertical burrows; various bottoms, mainly in sandy mud. 0-40 m. Produces wormcasts , which resemble those of Heteromastus and Arenicola.